1. Field of the Invention
The present invention relates to an apparatus using HDDs (Hard Disk Drives) for storing stream data and to a data reading method applied to the apparatus.
2. Description of the Related Art
Recently, an HDD array unit including a plurality of HDDs has been used in a broadcasting station and in post-production to obtain a large capacity for a storage apparatus that stores stream data such as AV (Audio/Video) data.
For example, such HDD array unit is included in an AV server used as an editing system and broadcasting system in a broadcasting station. The AV server has a plurality of input/output ports for AV data, and transfers the AV data at a high speed between the input/output ports and the HDD array unit.
High operational reliability and real-time responsiveness may be required for the AV server, since the AV server is supposed to operate continuously for 24 hours a day and 365 days a year and, in addition, an interruption or delay of video and audio is not permitted while programs are on-air.
However, the HDD is a device whose operational reliability and real-time responsiveness (response performance) are not so high. Because of that, the AV server includes the HDD array unit of a RAID (Redundant Arrays of Inexpensive Disks) configuration having redundancy, and further supports functions to cope with various failures. Data correction function using parity, data restoration function by rebuilding, data reassignment processing function (if a response delay occurs in a certain HDD, data thereof are output after being corrected using another HDD), and MTTR (Mean Time To Repair) reduction function by mounting a spare HDD can be supported in the AV server, for example.
Japanese Unexamined Patent Application Publication No. 2005-182658 discloses an example of a data recording and reproducing apparatus having a RAID configuration for storing AV data.